Abstract:

This talk explores the unique non-equilibrium phenomena in quantum many-body systems with long-range interactions, driven by recent experimental advancements. We will review the equilibrium properties of long-range interacting quantum spin systems, focusing on the variable-range quantum XY model and its equilibrium phase diagram. The impact of finite-range interactions on the quantum paramagnetic and ferromagnetic phases will be examined. The core of the talk addresses out-of-equilibrium dynamics, including the spreading of quantum correlations, slowdown of entanglement dynamics, suppression of thermalization, and the appearance of long-lived metastable states. The stabilization of non-equilibrium phases by periodic driving, such as discrete time crystals, will also be discussed.

This talk aims to provide a comprehensive overview of recent advances, emphasizing the need for a unifying framework to connect few-body mean-field physics with many-body physics of quasi-local interactions, with implications for future quantum-technological applications.

Biography:

Nicolò Defenu is an Italian physicist specializing in theoretical physics, particularly in quantum many-body systems and critical phenomena. He completed his BSc and MSc with honors at Sapienza University of Rome and earned his PhD from the International School for Advanced Studies (SISSA) in Trieste in 2017. After his PhD, Defenu held postdoctoral positions at the Institute for Theoretical Physics in Heidelberg and ETH Zurich. Among several grants and fellowships, he received the ERC Starting Grant on 2022 and, one year later, became an assistant professor at ETH Zurich. His research focuses universality, low-energy physics and quantum technology.